Solvation of tetraethyl- and tetrabutylammonium bromides in aqueous acetone and aqueous hexamethyl phosphoric triamide mixtures in the water-rich region

摘要

The enthalpies of solutions of tetraethylammonium and tetrabutylammonium bromides in the water-rich region of the water-acetone and water-hexamethyl phosphoric triamide mixed solvents have been measured at 25degreesC using a precise calorimetry system. The enthalpies of electrolyte solutions at infinite dilution were calculated using the Debye-Huckel theory. The enthalpies of solute transfer from water to the mixtures with acetone and hexamethyl phosphoric triamide were calculated. The enthalpy coefficients of solute-pair interactions with hexamethyl phosphoric triamide and acetone in aqueous solution were obtained using the McMillan-Mayer formalism. The values obtained were compared with those for other organic cosolvents. It was found that in aqueous solution the solutes show a strong tendency for hydrophobic interaction with cosolvent molecules, particularly in the water-hexamethyl phosphoric triamide system. [References: 28]